Hector J. Carlo

Storage yard operations in container terminals: Literature overview, trends, and research directions

Inbound and outbound containers are temporarily stored in the storage yard at container terminals. A combination of container demand increase and storage yard capacity scarcity create complex operational challenges for storage yard managers. This paper presents an in-depth overview of storage yard operations, including the material handling equipment used, and highlights current industry trends and developments. A classification scheme for storage yard operations is proposed and used to classify scientific journal papers published between 2004 and 2012. The paper also discusses and challenges the current operational paradigms on storage yard operations. Lastly, the paper identifies new avenues for academic research based on current trends and developments in the container terminal industry.

Transport operations in container terminals: Literature overview, trends, research directions and classification scheme

Internal transport operations connect the seaside, yard side, and landside processes at container terminals. This paper presents an in-depth overview of transport operations and the material handling equipment used, highlights current industry trends and developments, and proposes a new classification scheme for transport operations and scientific journal papers published up to 2012. The paper also discusses and challenges current operational paradigms of transport operations. Lastly, the paper identifies new avenues for academic research based on current trends and developments in the container terminal industry.

Optimizing inbound and outbound door assignments in less-than-truckload crossdocks

This study is concerned with inbound and outbound trailer-to-door assignments in crossdocks, which are used by many transportation companies as a redistribution point. A Simulated Annealing (SA)-based heuristic procedure to determine the door assignments in order to minimize the overall material handling workload in a rectangular crossdock is presented. The SA heuristic addresses congestion concerns as well as robustness concerns in a worst-case sense. Using internally generated data, and square versus narrow shapes, the SA heuristic is evaluated against optimal solutions (with up to 20 doors) and solutions obtained from a pairwise exchange, steepest-descent procedure (with up to 96 doors). The SA heuristic performs well in all problems tested. A linear mixed-integer program formulation for the general rectilinear-quadratic assignment problem is also presented. Lastly, the SA heuristic is applied at a 118-door crossdock operated by Con-way. The door assignment obtained with the SA heuristic outperforms the current door assignment by approximately 35% on data sets provided by Con-way.

Sequencing Two Cooperating Automated Stacking Cranes in a Container Terminal

The containerized trade market is growing rapidly with the uprising of the Far East. Container ports worldwide should be responsive by developing tools to handle these massive volumes of containers in order to retain their level of competitiveness. One of the areas in a container terminal that is highly affected by the increase in the demand of containers is the stack. The stack is used to temporarily store containers upon further transport to their destination. This study is concerned with scheduling sea and landside storages and retrievals in a stack with two cooperating automated stacking cranes working in a single block. We present a mathematical model to minimize the makespan for both cranes. Both an algorithm to derive a lower bound for the makespan and a simulated-annealing based heuristic are proposed to efficiently solve the problem. Numerical experiments show that the solutions of the heuristic method are within 2% of the lower bound for large instances.

Synchronization in cross-docking networks : A research classification and framework

Cross-docking is a distribution strategy that enables the consolidation of less-than-truckload shipments into full truckloads without long-term storage. Due to the absence of a storage buffer inside a cross-dock, local and network-wide cross-docking operations need to be carefully synchronized. This paper proposes a framework specifying the interdependencies between different cross-docking problem aspects with the aim to support future research in developing decision models with practical and scientific relevance. The paper also presents a new general classification scheme for cross-docking research based on the inputs and outputs for each problem aspect. After classifying the existing cross-docking research, we conclude that the overwhelming majority of papers fail to consider the synchronization of local and network-wide cross-docking operations. Lastly, to highlight the importance of synchronization in cross-docking networks, two real-life illustrative problems are described that are not yet addressed in the literature.

Integrating Reconfiguration Cost Into the Design of Multi-Period Scalable Reconfigurable Manufacturing Systems

A reconfigurable manufacturing system (RMS) that is designed specifically to adapt to changes in production capacity, through system reconfiguration, is called a scalable-RMS. The set of system configurations that a scalable-RMS assumes as it changes over time is called its configuration path. This paper investigates how to determine the optimal configuration path of a scalable-RMS that minimizes investment and reconfiguration costs over a finite horizon with known demand. First, a practical cost model is presented to compute the reconfiguration cost between two scalable-RMS configurations. This model comprehends labor costs, lost capacity costs, and investment/salvage costs due to system reconfiguration and ramp up. Second, the paper presents an optimal solution model for the multiperiod scalable-RMS using dynamic programming (DP). Third, a combined integer programming/dynamic programming (IP-DP) heuristic is presented that allows the user to control the number of system configurations considered by the DP in order to reduce the solution time while still providing a reasonable solution. Numerical problems involving a two-stage and a three-stage scalable-RMS are solved using the DP and IP-DP methodologies. Experimental results suggest that the DP approach, although it is optimal, is not computationally efficient for large problem sizes. However, the combined IP-DP approach offers reasonable results with much less computational effort.

Invited ReviewSynchronization in cross-docking networks: A research classification and framework

Cross-docking is a distribution strategy that enables the consolidation of less-than-truckload shipments into full truckloads without long-term storage. Due to the absence of a storage buffer inside a cross-dock, local and network-wide cross-docking operations need to be carefully synchronized. This paper proposes a framework specifying the interdependencies between different cross-docking problem aspects with the aim to support future research in developing decision models with practical and scientific relevance. The paper also presents a new general classification scheme for cross-docking research based on the inputs and outputs for each problem aspect. After classifying the existing cross-docking research, we conclude that the overwhelming majority of papers fail to consider the synchronization of local and network-wide cross-docking operations. Lastly, to highlight the importance of synchronization in cross-docking networks, two real-life illustrative problems are described that are not yet addressed in the literature.

Framework for Modeling Urban Restoration Resilience Time in the Aftermath of an Extreme Event

AbstractThe impacts of extreme events continue long after the emergency response has terminated. Effective reconstruction of supply-chain strategic infrastructure (SCSI) elements is essential for postevent recovery and the reconnectivity of a region with the outside. This study uses an interdisciplinary approach to develop a comprehensive framework to model resilience time. The framework is tested by comparing resilience time results for a simulated EF-5 tornado with ground truth data from the tornado that devastated Joplin, Missouri, on May 22, 2011. Data for the simulated tornado were derived for Overland Park, Johnson County, Kansas, in the greater Kansas City, Missouri, area. Given the simulated tornado, a combinatorial graph considering the damages in terms of interconnectivity between different SCSI elements is derived. Reconstruction in the aftermath of the simulated tornado is optimized using the proposed framework to promote a rapid recovery of the SCSI. This research shows promising results when...

An Analytical Model for Conveyor-Based Material Handling System With Crossovers in Semiconductor Wafer Fabs

This paper proposes a queueing-based analytical model useful in the design of closed-loop conveyor-based automated material handling system (AMHS), which has been identified as an effective material handling alternative in next-generation semiconductor wafer fabrication facilities. The model presented in this paper represents practical hardware considerations of the AMHS, such as turntables and crossovers. The objective is to accurately estimate the expected work-in-process (WIP) on the conveyor, queueing delays due to congestion at intersection points, as well as assessing the conveyor system stability. A four-phase approach is used to estimate the WIP. The proposed model is applied to the SEMATECH virtual 300 mm wafer fab. Experimental results demonstrate that in the worst case where the maximum number of crossovers is used and the traffic on the conveyor is high, the analytical model performs very well with average relative errors of 4.2%.

An analytical model for conveyor based amhs in semiconductor wafer fabs

This paper proposes an analytical model useful in the design of conveyor-based automated material handling systems (AMHS) to support semiconductor manufacturing. The objective is to correctly estimate the work-in-process on the conveyor and assess the system stability. The analysis approach is based on a queuing model, but takes into account details of the operation of the AMHS including turntables. A numerical example is provided to demonstrate and validate the queuing model over a wide range of operating scenarios. The results indicated that the analytical model estimates the expected work-in-process on the conveyor with reasonable accuracy.